Gel permeation chromatography is a form of chromatography which fractionates polymers and determines their molecular weight and molecular weight distribution. It is a type of liquid-solid elution chromatography that uses a column packed with an inert porous matrix which is eluted with a compatible solvent. This technique has been used for fractionating polymers since the separation is made according to molecular size or weight, based on the degree to which each molecular species is able to diffuse into the porous matrix. In this manner, the largest molecular species, or molecular weight fraction, penetrates the matrix the least and is eluted first.
U.S. Pat. No. 3,326,875 discloses the use of this method with swellable polystyrene beads to separate nonionic, high molecular weight hydrophobic polymers and U.S. Pat. No. 3,962,206 discloses the use of this technique with treated swellable polystyrene beads to separate ionic polymers. While the swellable quaternized styrene beads disclosed in U.S. Pat. No. 3,962,206 have been successfully used to fractionate cationic polymers, they have several disadvantages. For example, the swellable gel is not readily adaptable to high speed techniques of gel permeation of chromatography; bis-chloromethylether, which is used in the synthesis of the quaternized gel, is a carcinogen requiring special handling; pore sizes greater than 2000 A are not obtainable so that very high molecular weight polymers cannot be fractionated; eluting solvents cannot be changed over a wide range since irreversible collapse of the gel is easily effected; and the presence of hydrophobic regions has been observed to cause adsorption of cationic polymers which also have hydrophobic regions, as for example partially quaternized poly(2-vinylpyridine).
Accordingly, it is an object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers.
It is a further object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers which may be prepared by simple, rapid, reproducible and non-hazardous procedures.
It is still a further object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers which can be used with a wide variety of aqueous organic eluents and is stable to strongly acid eluents over an extended period of time.
It is another object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers that is rigid and non-compressible or non-swellable, thereby permitting utilization in high speed techniques.
It is still another object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers which does not adsorb these polymers.
It is still another object of this invention to provide a porous support for the gel permeation chromatography of cationic polymers which can fractionate the highest molecular weight polymers presently known.